We count on our police, firefighting and emergency medical response teams every day. Ambulance and fire department emergency response teams save countless lives and prevent property damage. Emergency response teams are able to help because of their skills, their training and their equipment. In the highly demanding world of front line police officers, fire fighters and emergency medical technicians, emergency equipment must work every time with practically 100% reliability.
Operating an emergency vehicle is one of the most common functions performed by today's fire and emergency service organizations. Yet, it is also one of the most dangerous. Collisions involving emergency vehicles and personal vehicles injure many people each year. Effective emergency response vehicle warning systems such as rooftop-mounted light bars, sirens, and the like, allow emergency response personnel to respond more effectively and safely. Manufacturers of emergency response vehicle equipment such as emergency warning lights, light bars, sirens, and the like, have spent considerable time and effort developing effective systems for warning of oncoming emergency response vehicles so motorists and pedestrians can get out of the way. Municipalities and governmental entities spend many millions of dollars each year to equip their emergency response teams with the most reliable, most effective warning systems available.
FIG. 1 shows an example of a marked or unmarked emergency response vehicle 10, including a conventionally wired light bar 12 on its roof 14 and conventionally wired grill and trunk accessories. Light bar 12 is a conventionally-designed light bar of the type most of us have seen on police cruisers, fire department vehicles, ambulances, tow trucks, emergency medical personnel vehicles, and the like. Light bar 12 can, for example, include conventional features such as for example low level flashers, strobe lights, rotating lights, illumination lights, speaker or other audible warning indicators, sweeping intersection lights, etc. One example is the MX 7000 manufactured by CODE 3 of St. Louis Mo. See, for example, U.S. Pat. Nos. 6,595,669; 6,585,399; 6,582,112; 6,461,022; 6,140,918; 6,081,191; D492,047; D489,466; D476,253; D460,950; D442,106; D427,537 and D410,402; and U.S. Patent Publication Nos. 2003/0007356, 2003/0012032 and 2005/0007784. Additional light and/or warning systems installed on-board the vehicle include grill mounted flashers, strobes or the like 16, trunk-mounted flashers, strobes or the like 18 and a conventional console-mounted switch box controller 20
Automobile manufacturers such as Ford, General Motors, Chrysler and others typically manufacture special “police interceptor” versions of standard passenger vehicles. Such police interceptors often provide more powerful engines and alternators, heavy duty suspension and frame, spotlights, and other special features. One option sometimes provided is a light bar connector for providing power to a roof-mounted light bar, which consists of a power cable coming directly from the vehicle battery, which is left unterminated between the headliner and vehicle roof. However, such manufacturers typically do not ship emergency response vehicles with light bars already installed. Instead, oftentimes, the purchasing governmental entity (e.g., local police department, fire department, etc.) may install (or contract for installation of) such special equipment as required by particular emergency response personnel. Different police departments may make different choices concerning manufacture and type of light bar, siren, and other special emergency response equipment. In general, such equipment is not necessarily installed at the automobile manufacturer's factory, but rather is often installed later as part of an after-market vehicle customization process. Such customization can end up being expensive and time consuming because of the additional wiring and other vehicle customization that may be required.
As shown in prior art FIG. 1, one prior art approach to controlling light bars and other auxiliary equipment was generally to run an extensive set of multi-conductor cabling throughout the vehicle from a switch box controller (e.g., of the type shown in FIG. 1A) to the device or devices being controlled. The FIG. 1A exemplary prior art switch box controller 20 in this exemplary illustration includes a heavy single (12 V) or dual (+12V, ground) power input connection (e.g., heavy gauge such as AWG #4, #6, or #8) from the vehicle battery 22. Switch box controller 20 switches the incoming vehicle battery power connection via various switches including, for example, a slider switch 24, also known as a progressive switch, and rocker-type ON/OFF switches 26 as is conventionally known.
The exemplary illustrative prior art FIG. 1 & 1A switch box controller 20 outputs its switched power outputs through a multi-conductor cable bundle 28 having a separate conductor for each of the various devices being controlled. For example, a conductor output by the switchbox controller 20 might be used to control the light bar 12 rotators, another output might be used to control light bar 12 alternating flashers, still other conductors might be used to control left and right alley lights, take down lights, a Priority Green optical preemption emitter, etc. Typically, multiconductor cable 28 may comprise a 13-conductor (or more) thick cable with ground.
While this design is highly reliable and has worked well for a number of years, it has the disadvantage that the resulting multi-conductor bundle of cables must be routed throughout the vehicle to the devices being controlled. FIG. 2 shows one example of what can be involved in installing conventional light bars and associated control equipment in a standard conventional police interceptor-type vehicle. Generally, it is typically necessary for the after-market installer to run a multi-conductor wiring harness from the control interface unit on the console or dashboard through the vehicle in between the headliner and inside of the vehicle roof to the light bar. As FIG. 2 illustrates, this may involve an extensive amount of disassembly of the vehicle including, but not limited to, removal of seats, dashboard portions and the like. All of these operations are time consuming and therefore are not only expensive but may delay operational use of the vehicle by emergency response personnel. Such cable routing can be costly due to the need to conceal the cables within headliners and other interior portions of the vehicle. Such installation may require a number of hours of work by a skilled technician. It is not unusual for initial installation efforts to be unsuccessful, requiring the partial or entire disassembly/reassembly process to be repeated in order to relieve crimped cables, bad connections, cosmetic bumps and blemishes, etc. If such wiring fails after installation, the same sort of disassembly process may be required to repair or replace the wiring harness. This can result in downtime during which the vehicle cannot be used. The same type of extensive customization process may be required for other emergency type vehicles such as tow trucks, volunteer fire department vehicles, emergency medical vehicles and the like.
It would be desirable to provide a more easily installed yet highly reliable communications link to allow the user control interface within the vehicle to communicate information signals to the light bar without the need to run additional wiring.
The technology herein provides a way to use power wiring to a light bar or other device for delivering power from an automobile battery or other power supply as a path for communicating information such as control signaling.
In one exemplary illustrative non-limiting implementation shown in FIG. 3, an information signal to be communicated to a roof-mounted light bar or other electrical or electronic device travels over the vehicle's or other environment's power bus or other power conductor. In one exemplary illustrative non-limiting implementation, a modulated current load draws power supply current in an amount that is instantaneously responsive to at least some characteristic of the information signal to be communicated. This modulated current loading induces the vehicular or other power supply (e.g., DC battery) to modulate its output voltage in a manner that is responsive to the modulated current loading. A voltage sensor and demodulator also connected to the power bus senses the resulting voltage fluctuations and demodulates those fluctuations to recover or regenerate the original information signal. The recovered information signal may be used for any purpose including, but not limited to, controlling aspects of the operation of an emergency vehicle light bar or other audible and/or visual warning system or other device. The data sender and data receiver can be co-located to provide a full duplex or half duplex powerline communicated transceiver.
Those skilled in the art understand that one of the challenges to communicating signaling within a vehicle relates to the substantial amount of electrical noise the vehicle generates. Alternators, heater fan motors, ignition systems and light bar rotators all typically generate substantial amounts of noise that can interfere with signal communications from one point within a vehicle to another. Communications techniques provided by the illustrative non-limiting exemplary implementations described herein are able to communicate signals effectively and reliably over the main power bus used to supply power to all systems on board the vehicle. In accordance with one exemplary illustrative non-limiting alternate implementation, additional switches are provided to synchronously or asynchronously disconnect noisy vehicle loads from the power bus from time to time (e.g., during data transmissions) in order to reduce the amount of noise the voltage sensor/demodulator sees. Such additional techniques may be helpful in some circumstances to achieve better performance.
In accordance with an additional exemplary illustrative non-limiting implementation, a finite power-based powerline communications method comprises a transmitting method/arrangement and a receiving method/arrangement that can be used separately and/or together. The powerline transmitter makes use of the inability of a given power supply (e.g., a vehicle's 12 volt battery) to provide a completely voltage regulated output under a modulated current induced load, such that the power supply is power-reactive to said load. The operation of the transmitter produces a corresponding voltage mirror of the induced current modulation throughout the electrical system. To improve reception, a receiver located on the power line may increase the signal-to-noise ratio by momentarily removing some or all current-drawn loads and thus increasing the line impedance such that the filtering to extract a given transmitter signal is decreased while signal integrity is increased.